The frozen aid "included some indirect support for the White Helmets as well as rebuilding and recovery funds for others," the group posted on Twitter. "We hope all Syria funds will resume soon."

Following Trump's remarks on leaving Syria the White House had said the US would keep a presence until Isil is completely defeated, but that the mission was "coming to a rapid end" and that countries in the region would have to play a larger role.

The White Helmets is composed of several thousand volunteers who have been hailed for saving thousands of lives, often racing to evacuate the wounded from rubble after shelling by government forces.

A Netflix documentary on the group titled "The White Helmets" won an Oscar in 2016.

The rescue workers have been the target of frequent attacks by pro-government and Russian critics who accuse them of links with Al-Qaeda and other extremist groups that operate rebel areas.